The present invention relates to a method for raising edible animals such as edible domestic animals and hatchery fish, wherein a dried fine powder of plant tissues such as stems and leaves of Stevia is added to feed in small amounts. Fish meat and domestic animal meat of the animals raised by the method of the invention has a reduced exudation of meat juice when stored, thus being able to provide goodtasting, excellent edible meat. Further, when fowls are raised by the method of the invention, eggs thereof are prevented from being broken.
It is known that Stevia leaves contain strong sweetening components such as stevioside and rebaudioside. On the other hand, Japanese Unexamined Patent Publication (TOKU KAI SHO) No. 62-108790 (1987) discloses that addition of a fine Stevia powder in which a Stevia leaf powder was mixed with a Stevia stem powder at a ratio of 10% to 40% to feed for cattle, horse and swine caused production of fat-rich, concentrated, good-tasting milk in milk cows. Japanese Examined Patent Publication (TOKU KO HEI) No. 7-13022 discloses medicines containing as active ingredients fermented, concentrated solutions extracted from Stevia stems for treating disorders of digestive organs of domestic animals and for improving physical conditions thereof, which treat adaptive diseases, oligopepsia, hyperacidity, diarrhea, loose feces, gingivostomatitis, constipation and intestinal disorders, increase digestion and appetite, and improve hair gloss, meat quality, milk quality, estrus and occurrence of menstruation, by drinking. As materials to be added to feed, fermented Stevia solutions have been used, active ingredients of which have been extracted from stems of Stevia with boiling water and fermented over a period of half a year or more. This takes a lot of labor and time, naturally resulting in an increase in cost to cause unsuitable use as feed for industrial animals.
Then, finely pulverized products of the whole plant tissues of Stevia including stems and leaves have been studied. The studies have revealed effects not taught in the prior art, such as a reduction in exudation of meat juice of fish meat or domestic animal meat, keeping of freshness, retardation of putrefaction and prevention of egg breakage.
According to the present invention, there is provided a method for raising an edible animal, in which a finely pulverized product of a plant tissue of Stevia is added to feed in an amount of 0.5% to 7% by weight, thereby preventing exudation of meat juice from meat of the edible animal, decreasing fat content without turning meat of the edible animal stale, producing DHA-containing meat of the edible animal, or preventing an egg of a fowl (preferably, a hen""s egg) from being broken.
The present invention further provides a feed additive for domestic animals, domestic fowls and hatchery fish, which comprises a dried, finely pulverized product of a plant tissue of Stevia, and preferably further comprises an organic acid in addition to the dried, finely pulverized product of the plant tissue of Stevia.
The present inventor has discovered the fact that exudation of meat juice is reduced in cuts of meat and the taste thereof is also improved, by adding a dried, finely pulverized product of a plant tissue of Stevia to feed for hatchery fish and domestic animals such as cattle, horse and swine in an amount of 10% by weight or less, preferably 2% to 3% by weight, thus completing the invention. This phenomenon has been observed in domestic animal meat, but also in fish meat. Exudation of meat juice from the resulting fish meat has also been reduced by raising fish, and giving feed to hatchery fish containing a dried, finely pulverized product of a plant tissue of Stevia. Domestic animal meat having a low fat content can be obtained without turning the meat stale. Further, DHA (docosahexaenoic acid) has been detected from the domestic animal meat obtained by the invention. There is no precedent that DHA is detected from meat of domestic animals such as swine.
Previously, 10% to 15% of eggs have been broken until eggshells are solidified after fowls have laid the eggs. This is a serious loss to the poultry raising industry. Accordingly, calcium-rich feed is given for reducing the breaking ratio of eggs. However, calcium metabolism does not catch up to egg production in the present state that the egg production rate is increased to near the extreme limit. There is therefore a limit on a decrease in the breaking ratio of eggs. Even if a large amount of a calcium ingredient is added to feed, it does not contribute to a decrease in the breaking ratio of eggs when added in an amount exceeding a certain value. It has therefore been considered that the physiology of hens cannot be adapted to the present mass egg production with respect to the calcium ingredient.
However, when the edible animals are raised and given feed to which the fine powder of Stevia is added, the breaking ratio of eggs has successfully been reduced to 2% to 3% without decreasing the number of laid eggs. Although the active ingredients of the finely pulverized products of Stevia used in the invention are not specified, they are considered to have a function of enhancing calcium metabolism, deducing from the effect.
Stevia used as a raw material in the invention is a perennial plant of Compositae (Asteraceae), which is native to South America and called Stevia Rebaudiana Bertoni, and includes its relative plants. Experiments have indicated that the active ingredients are contained in grown plant tissues, preferably in the whole plant tissues before bearing of buds, and in particular are contained in stems and leaves. The active ingredients are also contained in roots and young plants, in which they are contained in an amount of about ⅕ to about {fraction (1/10)} the weight of stems. For obtaining the finely pulverized products of Stevia, portions above the ground of grown Stevia, preferably Stevia before the bearing of buds, are harvested, dried and finely pulverized. There is no limitation on the method for drying and finely pulverizing them, as long as they are dried without being exposed to the rain or dew. In general, stems are separated from leaves and cut. The stems and the leaves are finely pulverized separately. A method of finely pulverizing them after drying is generally efficient. They are dried to a water content of 12% or less, preferably 10.5% or less, and finely pulverized to a particle size of 100 xcexcm or less, preferably 50 xcexcm or less. In general, smaller particle size results in effective utilization of the active principle. For easy handling, the fine powder may be granulated into granules.
When an organic acid is added to the fine Stevia powder thus obtained, the effects are more heightened. The organic acids include lactic acid, citric acid, tartaric acid, succinic acid, malic acid and propionic acid. Although cattle and horses are herbivorous animals, there is recently a tendency to give high-fat feed to them in a state that the feed does not load the rumen, such as rumen bypass, for accelerating the growth of them. When the finely pulverized products of the plant tissues of Stevia are used, they are added to feed for cattle, swine, fowls and horse. Further, they are also preferably used as feed additives for hatchery fish such as trout, young yellowtails and eels.
Although the amount of the fine Stevia powder used varies depending on the kind of animal, the degree of growth and the purpose, it is generally from 0.5% to 7% by weight, and preferably from 1% to 5% by weight, based on feed. Less than 0.5% by weight results in insufficient exhibition of the effects of the fine Stevia powder, whereas exceeding 7% by weight leads to no observation of the effects proportional to the amount of the fine Stevia powder added.